Creatinine Clearance Calculator

Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer Last updated: August 20, 2026

Disclaimer: This calculator is provided for informational and educational purposes only and does not constitute financial, medical, legal, or other professional advice. Always consult a qualified professional before making decisions based on these results.

📚 Confused about how this is calculated? Read the full Clearance: The Beautiful Fiction of Cleaned Blood →

The Formula That Refuses to Retire

Cockcroft-Gault was published in 1976, predates the equations that were meant to supersede it, and is still specified by name in the prescribing information of a long list of drugs. The reason is pragmatic rather than sentimental: many pharmacokinetic dosing studies were conducted using Cockcroft-Gault clearance as the reference, so the thresholds printed on those labels only mean what they say if you compute clearance the same way. Newer is not automatically compatible.

The Formula

The Cockcroft-Gault equation, exactly as implemented here:

CrCl (mL/min) = ( (140 − Age) × Weight (kg) × Sex Factor ) ÷ ( 72 × Serum Creatinine (mg/dL) )

Sex Factor = 0.85 for female, 1.0 for male

Three things are worth noticing. Clearance falls linearly with age, so every decade costs a fixed slice. It rises linearly with weight, which is why the choice of body weight to enter matters enormously. And it falls with the reciprocal of creatinine — doubling creatinine halves the estimate, no matter where you start.

Computed Clearance Reference

All values below were calculated with the formula above at a fixed 70 kg body weight:

Cockcroft-Gault CrCl in mL/min at 70 kg body weight
Age	Scr 0.8 (M / F)	Scr 1.0 (M / F)	Scr 1.5 (M / F)	Scr 2.0 (M / F)
30	133.7 / 113.6	106.9 / 90.9	71.3 / 60.6	53.5 / 45.5
50	109.4 / 93.0	87.5 / 74.4	58.3 / 49.6	43.8 / 37.2
70	85.1 / 72.3	68.1 / 57.8	45.4 / 38.6	34.0 / 28.9
80	72.9 / 62.0	58.3 / 49.6	38.9 / 33.1	29.2 / 24.8

Creatinine (Scr) in mg/dL. Because clearance scales linearly with weight, a 50 kg patient's figure is these values × 50/70; a 90 kg patient's is these values × 90/70.

The Weight Question

The single largest source of disagreement between two people computing Cockcroft-Gault on the same patient is not the formula — it is which weight went into it. The 1976 paper used actual body weight, but applying actual weight in obesity inflates the estimate, because adipose tissue does not generate creatinine the way muscle does. Many institutions therefore specify ideal or adjusted body weight above a defined threshold. This calculator uses whatever weight you enter, without adjustment, so the choice is yours to make and to state.

Note: This is general reference material for understanding a widely published formula, not medical advice and not a basis for dosing. Real renal dose adjustment depends on the specific drug, the weight convention your institution specifies, and clinical context. Consult a pharmacist or physician.

Cockcroft-Gault Versus eGFR

How the two renal estimates differ
	Cockcroft-Gault	CKD-EPI eGFR
Reports	Creatinine clearance	Glomerular filtration rate
Units	mL/min	mL/min/1.73m²
Uses weight	Yes	No
BSA-normalised	No	Yes
Typical role	Drug dose adjustment	CKD staging and monitoring

They answer related but distinct questions, which is why both remain in routine use rather than one having displaced the other.

Where This Calculation Matters

Renally cleared drugs — anticoagulants, several antibiotics, and many others carry label thresholds expressed in Cockcroft-Gault mL/min.
Older patients — the (140 − Age) term makes explicit how much clearance declines with age even when creatinine looks unremarkable.
Teaching pharmacokinetics — the formula's linear and reciprocal terms make dose-adjustment logic unusually easy to reason about.

How to Use This Calculator

Enter Age (years) — must be under 140 for the equation to return a positive value.
Enter Weight (kg), applying whichever weight convention you intend; the calculator does not adjust it.
Enter Serum Creatinine (mg/dL). Divide a µmol/L result by 88.4 to convert.
Select Sex to apply the 0.85 factor for female.
Select Calculate for the clearance in mL/min with the substituted equation shown.

Related Calculations

Run the same creatinine through the eGFR Calculator to see how the two estimates diverge, or see the Medication Dosage Calculator for the weight-based side of dose arithmetic.

Principles of Renal Function Estimation: Creatinine Clearance (CrCl)

A Creatinine Clearance (CrCl) calculator estimates the rate at which the kidneys filter creatinine from blood plasma. In clinical pharmacy and nephrology, the Cockcroft-Gault Creatinine Clearance equation is the FDA-mandated gold standard for adjusting drug dosages for renally eliminated medications.

The Fundamental Cockcroft-Gault Equation

Male CrCl (mL/min) = [ ( 140 - Age ) × Weight (kg) ] / [ 72 × Serum Creatinine (mg/dL) ]
Female CrCl (mL/min) = Male CrCl × 0.85 (Adjusts for lower female muscle mass)
Ideal Body Weight (IBW):
Men: IBW (kg) = 50.0 + 2.3 × ( Height in inches - 60 )
Women: IBW (kg) = 45.5 + 2.3 × ( Height in inches - 60 )
Adjusted Body Weight (if Actual Wt > 120% IBW): ABW = IBW + 0.40 × ( Actual Weight - IBW )

Step-by-Step Worked Calculation Example

Example: Calculating CrCl for an Elderly Female Patient

Problem: A 68-year-old female patient weighs 60 kg with a Serum Creatinine of S_cr = 1.20 mg/dL. Calculate her estimated Creatinine Clearance (CrCl).

Step 1: Apply the Cockcroft-Gault Equation for Females:

CrCl = [ ( 140 - 68 ) × 60 ] / [ 72 × 1.20 ] × 0.85

CrCl = [ 72 × 60 ] / [ 86.40 ] × 0.85 = [ 4,320 / 86.40 ] × 0.85 = 50.0 × 0.85 = 42.50 mL/min

Conclusion: With a CrCl of 42.5 mL/min (Moderate Renal Impairment), renally cleared antibiotics (e.g., Vancomycin, Ciprofloxacin) require dose reduction to prevent toxicity.

Clinical Limitations in Sarcopenia and Malnutrition

Because creatinine is a metabolic byproduct of skeletal muscle breakdown:

Frail, bedridden elderly patients with severe muscle wasting (sarcopenia) produce minimal daily creatinine, yielding falsely low serum creatinine levels (e.g., S_cr = 0.50 mg/dL).

This falsely inflates calculated CrCl, risking severe antibiotic overdoses. Clinical pharmacists round low serum creatinine values to 0.80 or 1.00 mg/dL or utilize 24-hour urine creatinine collections for accurate pharmacokinetic dosing.

Direct Oral Anticoagulant (DOAC) Dosing Rules

Cardiologists and clinical pharmacists adjust DOAC dosing based on Cockcroft-Gault CrCl:

Rivaroxaban (Xarelto): Reduce dose from 20 mg daily to 15 mg daily if CrCl is 15 to 50 mL/min; avoid if CrCl < 15 mL/min.
Dabigatran (Pradaxa): Reduce dose from 150 mg BID to 75 mg BID if CrCl is 15 to 30 mL/min.

Vancomycin Pharmacokinetic Trough Monitoring

In critical care infectious disease management, clinical pharmacists calculate patient CrCl to establish initial Vancomycin dosing intervals (e.g., Q8H for CrCl > 90 vs Q24H for CrCl < 30), preventing drug accumulation and nephrotoxicity.

CrCl Monitoring in ICU Septic Shock

Critically ill ICU patients receiving aggressive intravenous fluid resuscitation experience Augmented Renal Clearance (ARC: CrCl > 130 mL/min):

Clinical pharmacists recalculate CrCl daily, escalating beta-lactam antibiotic dosages to prevent subtherapeutic drug concentrations and treatment failure.

Renal Pharmacotherapy Safety

Accurately estimating Creatinine Clearance prevents dangerous drug accumulation and protects patient safety during prolonged courses of renally cleared medications.

Comprehensive Renal Function Assessment

Combining Cockcroft-Gault Creatinine Clearance with serum cystatin C confirmatory testing ensures comprehensive renal function characterization, optimizing individualized drug dosing across diverse patient populations.

Kidney-Safe Medication Dosing

Routine Creatinine Clearance estimation guides safe dosage adjustments for renally eliminated pharmaceuticals across all patient age groups.

Accurate renal function estimation remains fundamental to safe clinical pharmacotherapy.